The present invention generally relates to apparatus for encapsulating small doses of fluid contents and the contents themselves. More particularly, in a preferred embodiment, the present invention is directed to a gelatinous-like container system encompassing a single dose or charge of medication for oral administration.
A low aqueous solubility of a great number of medicaments is a source of inconvenience and further raises the overall cost of a course of treatment with any such low solubility medicament. Low aqueous solubility of a medicament often leads to low and unreliable systemic bioavailability.
Retinoids, that is, functional and structural derivatives of retinoic acid, have been successful in the treatment of acne, particularly nodular acne, psoriasis, disorders of Keratinion and oncology. However, the low aqueous solubility has limited the administration of the retinoids to their use in topical gels, creams, orals and the like.
A desired advantage of oral administration of retinoids is increased efficacy. Thus, in general, while the advantages of oral delivery or topical delivery of active agents are well known, oral administration of retinoids is made difficult by their low aqueous solubility, which results in decreased effectiveness in systemic drug delivery.
As set forth in an article by Humberstone and Charman, entitled, xe2x80x9cLipid-based Vehicles for the Oral Delivery of Poorly Water-Soluble Drugsxe2x80x9d, (Adv. Drug Del. Reviews 25, 1997, pp. 103-128), there are few commercial examples of lipid-based oral formulations, other than special cases, as for example, cyclosporin and the lipid-soluble vitamins. Reasons for the lack of commercial success include the complexity of the interfacial and physical chemistry. The article also reported that the results of different lipids and bioavailability are very drug specific. Accordingly, while the article appears to set forth general principles including emulsification techniques, there is, in fact, no general guidelines which can be relied on for developing an oral system for the delivery of a specific active agent, such as a retinoid, having low aqueous solubility.
In a preferred embodiment, the present invention is directed to a capsule system for the oral delivery of a retinoid having a low aqueous solubility and is more particularly directed to a capsule system for oral delivery of Tazarotene. The invention also includes a means for solubilizing retinoids and insuring effective systemic delivery of a retinoid drug.
In other words, the present invention provides a capsule system for active agents of low aqueous solubility in a form which is biologically available in a particularly advantageous way.
In a preferred embodiment, the present invention includes a capsule system for the oral delivery of an active agent having low aqueous solubility generally includes an active retinoid agent having low aqueous solubility and a vehicle for eliminating any need for initial active agent dissolution within the gastro-intestinal tract.
More particularly, the vehicle may comprise a liquid triglyceride which fully dissolves the active agent. In this manner, initial active agent dissolution within the gastro-intestinal tract is not necessary, because it is initially dissolved in the vehicle.
In addition, an emulsifier provides a means for promoting self-emulsification of the active agent and the vehicle in this gastro-intestinal tract. In the preferred embodiment, a capsuled shell provides a means for encapsulating the active agent vehicle means and emulsifier. The capsuled shell is formulated to open or dissolve upon ingestion into the gastro-intestinal tract and accordingly release the active agent and vehicle. At this point, the self-emulsification occurs thereby facilitating absorption through the gastro-intestinal wall thereby providing biological availability and systemic circulation of the active agent.
Preferably, the vehicle comprises a medium chain liquid triglyceride which, as hereinabove noted, initially, fully dissolves the active retinoid agent. More particularly, the vehicle may comprise a caprylic/capric triglyceride and the emulsifier may comprise co-emulsifiers, such as sorbitan monooleate and polysorbate 80. Other vehicles which may be suitable include: Ethyl oleate, Isopropyl myristate, Cetearyl octancate, Corn oil, Cottonseed oil, Safflower oil, Olive oil, Peanut oil, Soybean oil and Sesame oil. Other emulsifiers which may be suitable include: Sorbitan monolaurate, Sorbitan monopalmitate, Sorbitan monostearate and Polysorbates 20, 40 or 60.
Importantly, the co-emulsifiers are selected to match a hydrophilic/lipophilic balance (HLB) of the caprylic/capric triglyceride. This is important in order to promote the optimal emulsification of the triglyceride into the aqueous gastro-intestinal fluids and accordingly the absorption of the agent for systemic circulation.
More specifically, as hereinabove noted, the active retinoid agent may be Tazarotene and the vehicle further comprises an antioxidant, such as, for example, butylated hydroxyanisole. Other antioxidants which may be suitable include: Butylated hydroxytoluene, Tocopherols (Vitamin E), Propyl gallate, and Ascorbyl palmitate. Other active retinoid agents include, for example, Vitamin A and its natural and synthetic derivatives.
A capsuled shell, as hereinabove noted, further includes an opaque colorant to prevent degradation of a retinoid, such as Tazarotene, from exposure of the capsule system to harmful wavelength of light.
Also a part of the invention is a method for enabling delivery of an active agent having low aqueous solubility. The method includes the steps of providing an active retinoid agent having low aqueous solubility with the active agent dissolved in a vehicle in order to eliminate any need for initial active agent dissolution in the gastro-intestinal tract.
The method further includes steps of incorporating an emulsifier to the vehicle in order to promote self-emulsification of the active agent and vehicle in the gastro-intestinal tract and the step of encapsulating the active agent, vehicle and emulsifier with a capsule shell formulated to open upon ingestion into the gastro-intestinal tract.